A Closer Look at Climate Panel’s Findings on Global Warming Impacts

An illustration from the final draft of the forthcoming impacts report of the Intergovernmental Panel On Climate Change shows how warming from unabated greenhouse gas emissions (pink graph at left) steadily raises risks while emissions cuts curb warming and impacts. (Click for large version.)

Gillis’s piece focuses on the section on agricultural impacts of climate change. Please read it and return, keeping in mind that language could change before the final report is released in late March in Japan.

Here’s a sample of some other notable conclusions:

Human health:

Until mid-century, climate change will impact human health mainly by exacerbating health problems that already exist (high confidence), and climate change throughout the 21st century will lead to increases in ill-health in many regions, as compared to a baseline without climate change (high confidence). Examples include greater likelihood of injury, disease, and death due to more intense heat waves and fires; increased likelihood of under-nutrition resulting from diminished food production in poor regions; risks from lost work capacity and reduced labor productivity in vulnerable populations; and increased risks from food- and water-borne diseases. Positive effects will include modest improvements in cold-related mortality and morbidity in some areas due to fewer cold extremes, shifts in food production, and reduced capacity of disease-carrying vectors (medium confidence), but globally, positive inlpacts will be outweighed by the magnitude and severity of negative impacts (high confidence). The most effective adaptation measures for health in the near-term are programs that implement basic public health measures such as provision of clean water and sanitation, secure essential health care including vaccination and child health services, increase capacity for disaster preparedness and response, and alleviate poverty (very high confidence). For RCP8.5 [the high emissions scenario and warming track in the illustration above] by 2100, the combination of high temperature and humidity in some areas for parts of the year will compromise normal activities, including growing food or working outdoors (high confidence).

A closer look at the food findings:

Without adaptation, local temperature increases of 1 °C or more above pre-industrial levels are projected to negatively impact yields for the major crops (wheat, rice, and maize) in tropical and temperate regions, although individual locations may benefit (medium confidence). With or without adaptation, climate change will reduce median yields by 0 to 2% per decade for the rest of the century, as compared to a baseline without climate change. These projected impacts will occur in the context of rising crop demand, projected to increase by about 14% per decade until 2050…. Risks are greatest for tropical countries, given projected impacts that exceed adaptive capacity and higher poverty rates compared with temperate regions. Climate change will progressively increase inter-annual variability of crop yields in many regions.

On average, adaptation improves yields by the equivalent of ~15-18% of current yields, but the effectiveness of adaptation is highly variable (medium confidence). Positive and negative yield impacts projected for local temperature increases of about 2°C above preindustrial levels maintain possibilities for effective adaptation in crop production (high confidence). For local warming of about 4°C or more, differences between crop production and population-driven demand will become increasingly large in many regions, posing significant risks to food security even with adaptation.

Whatever climate change ends up throwing at us on top of today’s climate hazards, there are plenty of glaring opportunities now to cut vulnerability. Here’s the panel’s way of saying this:

In many cases, a first step towards adaptation to future climate change is reducing vulnerability and exposure to present climate through low-regrets measures and actions emphasizing co-benefits (high confidence). Available strategies and actions can increase resilience across a range of possible future climates while helping to improve human livelihoods, social and economic well-being, and environmental quality.

There’s much more, so I encourage you to download the draft and explore.

Attribution of observed impacts in the WGII AR5 links responses of natural and human systems to climate change, not to anthropogenic climate change, unless explicitly indicated.

In discussions of impacts in the leaked draft, the distinction between human, or anthropogenic, and "natural" climate change is only rarely made. To my eye, this greatly limits the significance of many findings given that the big questions for society still center on how quickly to curb greenhouse gas emissions. Roger A. Pielke, Jr., has published on the problems created for diplomacy and policy by varied definitions of "climate change" in the journal Environmental Science & Policy.]

One issue I didn’t see mentioned was population growth as a driver of vulnerability in regions like sub-Saharan Africa. So it was not surprising to see no mention of expanding access to family planning as a strategy for reducing stresses from climate extremes, or climate change, in such regions. That’s unfortunate, but unsurprising given how population is frequently unmentionable in the context of international discussions of climate change.